In one aspect, the invention relates to a process for selectively positioning fiber reinforcement in a composite article. In another aspect, this invention relates to a valve element formed from a composite material and having selectively positioned fiber reinforcement.
Thermopress molding is an extremely desirable technique to use to form articles from thermoplastic composite materials since it allows the use of long fiber reinforcemet. Long fiber reinforcement in composite articles generally provides highest performance properties. However, when the long fiber reinforcement is highly oriented, such as in the form of a woven mat, poor fiber flow during the molding operation leaves fiber deficient areas which are prone to premature failure.
Better fiber distribution results when random fiber mat is the reinforcement in a thermoplastic matrix. Random fibers enjoy higher mobility than highly oriented fibers and become well distributed throughout the molded articles. However, molded articles reinforced with random fibers are prone to failure at high stress points because random fibers do not impart the highest performance properties. A technique for selectively providing the high stress points of articles containing random fiber reinforcement with oriented fibers and/or a different loading of reinforcing fibers would be very desirable.